Well you are building hrs so you might as well do some decent hops.. How about:
The Scilly Isles will challenge you and is beautiful
Then stop at Lands End
Perranporth with a lovely approach over the cliffs
Dunkerswell as the Bacon, Brie and Cranberry sandwich is amazing
Compton Abbas is beautiful scenery and great food
Then back via Caernarfon
That would be the best part of 4 hrs flying in a 152, plus stopping and a great day out.